The surface characteristics and in vitro corrosion properties of nanocrystalline TiAlN coating deposited on biomedical Ti6Al4V alloy by cathodic arc evaporation were studied. The structure and surface morphology were analyzed using XRD and FE-SEM. The surface microhardness was characterized using microindentation. The in vitro corrosion was carried out in simulated body fluid and artificial saliva. The results exhibited that a TiAlN film was deposited with an enhanced surface hardness of 44.4 GPa, a elastic modulus of 419.9 GPa, and enhanced resistance to plastic deformation compared to uncoated alloy. The wetting angle of TiAlN coated surfaces ((86.27±2.2)°) was larger than that of uncoated Ti6Al4V surfaces ((70.61±1.25)°). Biocorrosion examinations revealed that TiAlN-coated Ti6Al4V alloy exhibited a significant positive shift of about 150 mV in corrosion potential with the notable reduction of about one order of magnitude in corrosion current density and higher charge transfer resistance, confirming the improved barrier performance. The surface, mechanical and corrosion performance of TiAlN coating was enhanced compared to uncoated alloy.